Polytype electroconductive powders

Abstract

The disclosure relates broadly to a new class or type of electroconductive powders (ECP), designated as Polytype ECP (PECP), comprising intimate mixtures of several types of ECP powders. PECP mixtures possess a lower electrical resistivity, or a higher electroconductivity, than would be expected from the weighted average of the component ECP powders. PECP are multi-component and may contain many different types of ECP. ECP components of the PECP can be selected from at least one member of the group consisting of crystallites of tin oxide containing antimony in solid solution, crystallites of antimony-containing tin oxide with uniformly distributed amorphous silica, two dimensional networks of crystallites of antimony-containing tin oxide in a unique association with amorphous silica or silica-containing material, filler materials, metal coated powders, conventional ECP materials such as carbon, aluminum powder, among others.

The following is claimed: 
     
       1. An electroconductive composition comprising 1) a mixture of A) particles of an electroconductive powder comprising antimony-containing tin oxide and B) separate particles of a non-electrically conducting filler selected from the group consisting of silica, titanium dioxide, mica, calcium carbonate, and mixtures thereof, in a ratio of electroconductive powder to non-electrically conducting filler of from about 98:2 to about 7:3, said mixture possessing a dry powder resistivity which is lower than the weighted average of its components, and said mixture dispersed in or applied onto 2) a matrix material selected from the group consisting of paints, varnishes, plastics, and paper. 
     
     
       2. The composition of claim 1 wherein the dry powder resistivity of said mixture is at least 5% lower than the weighted average dry powder resistivity of the components. 
     
     
       3. The electroconductive composition of claim 1 wherein the slope of a surface resistivity versus mixture weight loading curve is at least 5% less steep than that of the individual electroconductive powder component having the steepest slope measured over the same weight loading. 
     
     
       4. The electroconductive composition of claim 1 wherein the electroconductive powder is selected from the group consisting of crystallites of antimony-containing tin oxide, metal coated powders and two dimensional networks of crystallites of antimony-containing tin oxide in association with amorphous silica or silica-containing material. 
     
     
       5. The electroconductive composition of claim 1 wherein said electroconductive powder comprises a conducting coating of antimony-containing tin oxide on a core particle. 
     
     
       6. The electroconductive composition of claim 5 wherein the antimony content is less than about 12.5% by weight of tin oxide. 
     
     
       7. The composition of claim 1 wherein the transparency of said mixture is at least about 3% greater than the transparency of said individual components of the mixture. 
     
     
       8. The electroconductive composition of claim 5 wherein the core particle is selected from the group consisting of mica; silica; calcium carbonate; oxides of titanium, magnesium, calcium, barium, strontium, zinc, tin, nickel and iron; barium carbonate; strontium carbonate; calcium sulfate; barium sulfate; strontium sulfate, cordierite; anorthite; and pyrophyllite. 
     
     
       9. The electroconductive composition of claim 1 wherein the non-electrically conductive filler is selected from the group consisting of calcium carbonate; silica; mica; oxides of titanium, magnesium, calcium, barium, strontium, zinc, tin, nickel and iron; barium carbonate; strontium carbonate; calcium sulfate; barium sulfate; strontium sulfate, cordierite; anorthite; and pyrophyllite. 
     
     
       10. The composition of claim 1 wherein said mixture comprises a first component selected from the group consisting of mica platelets having an antimony-containing tin oxide layer and silica shells having an antimony-containing tin oxide layer, a second component selected from the group consisting of titanium dioxide having an antimony-containing tin oxide layer and amorphous silica having an antimony-containing tin oxide layer, and a third component of a non-electrically conductive filler.